What can I do to improve my 2nd system?

Without first hand examination of these devices, it is hard to say whether they preserve a rigid mount of the speaker while also providing some isolation, or whether they permit too much motion at the speaker base.  I did take a look at the Magico website. The footers on their speakers actually would seem to add stability to the cabinets, while also attempting to isolate the speaker from the floor.  If so, I certainly have no issue.  Like I said, I take issue with rubbery or springy speaker mounts.  But springy could work OK if the springs are very compressed under load so as to minimize the potential for amplifier energy to generate cabinet motion. I suppose it's a trade-off.

So far as I know, Newton’s 3rd Law of Motion still operates in the modern world, Relativity notwithstanding. What changes are the stories that audio entrepreneurs dish out to lure customers.

I have no idea what QLN or Magico do.  Can you elaborate?  I cannot believe that either company would countenance placing rubbery supports under their speaker cabinets, but I am all ears.  I have a better idea about Townshend ISO platforms.  They seem to constrain speaker movement while also claiming to isolate the cabinet.  I am not preaching against isolation. I am preaching against mushy or springy feet that allow the cabinet to move in response to a musical transient.  How could that be a good thing?  Has nothing to do with the type of speaker, in my thinking.

The above principle is another reason to get better speaker stands, and when you get them make sure your speakers are firmly anchored to them. I’d even put some lead weights on top of the speakers.

Remove any flexible footers from under any and all of your speakers. You want the speaker to be held firmly in a fixed physical position. Otherwise energy put into the speaker by the amplifier is partially being used up to move the speaker, rather than to move the speaker cones. This results in smearing. I know there are many who like to put cushiony devices like Springs and sorbothane, etc pillows under their speakers, but in my opinion this is plain wrong. The practice is encouraged by dealers and manufacturers, because of course it sells product.